On Nov 9, 2011, at 2:34 PM, Paul Hoadley wrote: > Hi Ramsey, > > On 10/11/2011, at 4:24 AM, Ramsey Gurley wrote: > >> On Nov 8, 2011, at 8:34 PM, Paul Hoadley wrote: >> >>> So the advice is that the intended delete rule(s) should operate on the >>> real relationship chain, not shortcut via the flattened relationship. >>> That's fine, but are Nullify and Do Nothing really interchangeable on a >>> flattened relationship, as it's almost suggested above? It's important >>> because the default is Nullify, so all flattened relationships have that >>> rule unless you change them. But depending on whether that rule is applied >>> before or after the rule(s) applied over the real relationship chain, >>> Nullify might end up giving you the wrong semantics. Shouldn't all >>> flattened relationships have a Do Nothing delete rule (at least by default)? > >> Not all... at least not flattened many to many. Those cascade. Which led >> me to a surprising find as well. The opposite side of that cascade is >> nullify, which I thought was incompatible with cascade. But, evidently, it >> works and I can see why it would be needed on the other side of the delete. > > Say I have two entities, User and Role, and a joining entity UserRole to > create a many-to-many relationship between them. So I have a relationship > 'userRoles' from User to UserRole (and a relationship 'userRoles' from Role > back to UserRole). I flatten the relationship on User, so I also have a > 'roles' relationship on that entity. > > Say I delete a User. I want User.userRoles to Cascade. And I want both > UserRole.user and UserRole.role to Nullify. And at that point, isn't the > work done? So in this case, wouldn't I want No Action on User.roles? And > hence isn't this a counter-example to your advice above? (It may well not > be—tell me if I'm wrong!) >
I looked a second time. The cascade is actually on the non-class property. The flattened is nullify... so maybe it would work with no action. I'm not recommending anything, just noting something I saw which seemed odd. Ramsey _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
